Air maintenance pumping tube and tire assembly

ABSTRACT

A groove defined by groove sidewalls is positioned within the bending region of a tire sidewall. An elongate air tube positioned within the sidewall groove is in contacting engagement with the groove sidewalls and resiliently squeezes and collapses segment by segment as the groove constricts segment by segment within the rolling tire footprint. A longitudinally oriented projecting locking rib extends from a tube sidewall and registers within a complementary configured and located detent extending adjacent the groove to deter lateral movement of the tube within the groove after insertion. An annular projecting ridge extends from the groove for engaging the sidewalls of the air tube to deter an axial movement of the tube within the groove after insertion.

FIELD OF THE INVENTION

The invention relates generally to air maintenance tires and, morespecifically, to an air maintenance and tire pumping assembly.

BACKGROUND OF THE INVENTION

Normal air diffusion reduces tire pressure over time. The natural stateof tires is under inflated. Accordingly, drivers must repeatedly act tomaintain tire pressures or they will see reduced fuel economy, tire lifeand reduced vehicle braking and handling performance. Tire PressureMonitoring Systems have been proposed to warn drivers when tire pressureis significantly low. Such systems, however, remain dependant upon thedriver taking remedial action when warned to re-inflate a tire torecommended pressure. It is a desirable, therefore, to incorporate anair maintenance feature within a tire that will maintain air pressurewithin the tire in order to compensate for any reduction in tirepressure over time without the need for driver intervention.

SUMMARY OF THE INVENTION

In one aspect of the invention, a groove defined by groove sidewalls ispositioned within the bending region of the first tire sidewall. Anelongate air tube positioned within the sidewall groove is in contactingengagement with the groove sidewalls and resiliently squeezes andcollapses segment by segment as the groove constricts segment by segmentwithin the rolling tire footprint. One or more longitudinally orientedprojecting locking ribs extend from a tube sidewall and registers withina complementary configured and located detent extending adjacent thegroove to deter lateral movement of the tube within the groove afterinsertion.

In another aspect, a pair of longitudinal ribs are directed in oppositedirections from tube sides and into respective complementary detentsadjacent the groove to deter lateral movement of the tube within thegroove.

According to another aspect, the tube further includes one or moreannular projecting ridges along the air tube for engaging the sidewallsof the groove to deter an axial movement of the tube within the grooveafter insertion.

DEFINITIONS

“Aspect ratio” of the tire means the ratio of its section height (SH) toits section width (SW) multiplied by 100 percent for expression as apercentage.

“Asymmetric tread” means a tread that has a tread pattern notsymmetrical about the center plane or equatorial plane EP of the tire.

“Axial” and “axially” means lines or directions that are parallel to theaxis of rotation of the tire.

“Chafer” is a narrow strip of material placed around the outside of atire bead to protect the cord plies from wearing and cutting against therim and distribute the flexing above the rim.

“Circumferential” means lines or directions extending along theperimeter of the surface of the annular tread perpendicular to the axialdirection.

“Equatorial Centerplane (CP)” means the plane perpendicular to thetire's axis of rotation and passing through the center of the tread.

“Footprint” means the contact patch or area of contact of the tire treadwith a flat surface at zero speed and under normal load and pressure.

“Groove” means an elongated void area in a tire dimensioned andconfigured in section for receipt of an elongate air tube therein.

“Inboard side” means the side of the tire nearest the vehicle when thetire is mounted on a wheel and the wheel is mounted on the vehicle.

“Lateral” means an axial direction.

“Lateral edges” means a line tangent to the axially outermost treadcontact patch or footprint as measured under normal load and tireinflation, the lines being parallel to the equatorial centerplane.

“Net contact area” means the total area of ground contacting treadelements between the lateral edges around the entire circumference ofthe tread divided by the gross area of the entire tread between thelateral edges.

“Non-directional tread” means a tread that has no preferred direction offorward travel and is not required to be positioned on a vehicle in aspecific wheel position or positions to ensure that the tread pattern isaligned with the preferred direction of travel. Conversely, adirectional tread pattern has a preferred direction of travel requiringspecific wheel positioning.

“Outboard side” means the side of the tire farthest away from thevehicle when the tire is mounted on a wheel and the wheel is mounted onthe vehicle.

“Peristaltic” means operating by means of wave-like contractions thatpropel contained matter, such as air, along tubular pathways.

“Radial” and “radially” means directions radially toward or away fromthe axis of rotation of the tire.

“Rib” means a circumferentially extending strip of rubber on the treadwhich is defined by at least one circumferential groove and either asecond such groove or a lateral edge, the strip being laterallyundivided by full-depth grooves.

“Sipe” means small slots molded into the tread elements of the tire thatsubdivide the tread surface and improve traction, sipes are generallynarrow in width and close in the tires footprint as opposed to groovesthat remain open in the tire's footprint.

“Tread element” or “traction element” means a rib or a block elementdefined by having a shape adjacent grooves.

“Tread Arc Width” means the arc length of the tread as measured betweenthe lateral edges of the tread.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by way of example and with reference tothe accompanying drawings in which:

FIG. 1; Isometric exploded view of tire and tube assembly.

FIG. 2; Side view of tire/tube assembly.

FIG. 3A through 3C; Details of outlet connector.

FIG. 4A through 4E; Details of inlet (filter) connector.

FIG. 5A; Side view of tire rotating with air movement (84) to cavity.

FIG. 5B; Side view of tire rotating with air flushing out filter.

FIG. 6A; Section view taken from FIG. 5A.

FIG. 6B; Enlarged detail of tube area taken from FIG. 6A, sidewall innon-compressed state.

FIG. 7A; Section view taken from FIG. 5A.

FIG. 7B; Enlarged detail of tube area taken from FIG. 7A, sidewall incompressed state.

FIG. 8A; Enlarged detail of the preferred tube & groove detail takenfrom FIG. 2.

FIG. 8B; Detail showing the preferred tube compressed and being insertedinto groove.

FIG. 8C; Detail showing the preferred tube fully inserted groove atribbed area of groove.

FIG. 8D; Exploded fragmented view of tube being inserted into ribbedgroove.

FIG. 9; Enlarged detail taken from FIG. 2 showing the “first” ribprofile area located on both side of the outlet to cavity connector.

FIG. 10A; Enlarged detail of groove with “first” rib profile.

FIG. 10B; Enlarged detail of tube pressed into “first” rib profile.

FIG. 11; Enlarged detail taken from FIG. 2 showing the “second” ribprofile area located on both side of the outlet to cavity connector.

FIG. 12A; Enlarged detail of groove with “second” rib profile.

FIG. 12B; Enlarged detail of tube pressed into “second” rib profile.

FIG. 13A; Enlarged view of a “second” embodiment of a tube & groovedetail.

FIG. 13B; Detail showing tube from FIG. 13A being compressed andinserted into groove.

FIG. 13C; Detail showing tube from FIG. 13A fully inserted into groove.

FIG. 14A; Enlarged view of a “third” embodiment of a tube & groovedetail.

FIG. 14B; Detail showing tube from FIG. 14A being compressed andinserted into groove.

FIG. 14C; Detail showing tube from FIG. 14A fully inserted into groove.

FIG. 15A; Enlarged view of a “forth” embodiment of a tube & groovedetail.

FIG. 15B; Detail showing tube from FIG. 15A being compressed andinserted into groove.

FIG. 15C; Detail showing tube from FIG. 15A fully inserted into groove.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1, 2, and 6A, a tire assembly 10 includes a tire 12,a peristaltic pump assembly 14, and a tire rim 16. The tire mounts inconventional fashion to a pair of rim mounting surfaces 18, 20 adjacentouter rim flanges 22, 24. The rim flanges 22, 24, each have a radiallyoutward facing flange end 26. A rim body 28 supports the tire assemblyas shown. The tire is of conventional construction, having a pair ofsidewalls 30, 32 extending from opposite bead areas 34, 36 to a crown ortire tread region 38. The tire and rim enclose a tire cavity 40.

As seen from FIGS. 2 and 3A, 3B, 3C, 6B and 8A, the peristaltic pumpassembly 14 includes an annular air tube 42 that encloses an annularpassageway 43. The tube 42 is formed of a resilient, flexible materialsuch as plastic or rubber compounds that are capable of withstandingrepeated deformation cycles wherein the tube is deformed into aflattened condition subject to external force and, upon removal of suchforce, returns to an original condition generally circular incross-section. The tube is of a diameter sufficient to operatively passa volume of air sufficient for the purposes described herein andallowing a positioning of the tube in an operable location within thetire assembly as will be described. In the configuration shown, the tube42 is of elongate, generally elliptical shape in section, havingopposite tube sidewalls 44, 46 extending from a flat trailing tube end48 to a radiussed leading tube end 50. The tube 42 is configured havinga longitudinal outwardly projecting pair of locking detent ribs 52 ofgenerally semi-circular cross-section and each rib extending alongoutward surfaces of the sidewalls 44, 46, respectively. As referenced inFIG. 8A, the tube 42 has a length L1 within a preferred range of 3.65 to3.8 mm; a preferred width of D1 within a range of 2.2 to 3.8 mm; atrailing end preferred width of D3 within a range of 0.8 to 1.0 mm. Theprotruding detent ribs 52, 54 each have a radius of curvature R2 withina preferred range of 0.2 to 0.5 and each rib is located at a positiondistance L3 within a preferred range of 1.8 to 2.0 mm of the trailingtube end 48. The leading end 50 of the tube 42 has a radius R1 within arange of 1.1 to 1.9 mm. The air passageway 43 within the tube 42 islikewise of generally elliptical cross-section having a length L2 withina preferred range of 2.2 to 2.3 mm; and a preferred width D2 within arange of 0.5 to 0.9 mm.

The tube 42 is profiled and geometrically configured for insertion intoa groove 56. The groove 56 is of elongate, generally ellipticalconfiguration having a length L1 within a preferred range of 3.65 to 3.8mm in complement to the elliptical shape of the tube 42. The groove 56includes a restricted narrower entryway 58 having a nominalcross-sectional width D3 within a preferred range of 0.8 to 1.0 mm. Apair of groove rib-receiving axial detent channels 60, 62 ofsemi-circular configuration are formed within opposite sides of thegroove 56 for complementary respective receipt of the tube locking ribs52, 54. The channels 60, 62 are spaced approximately a distance L3within a range of 1.8 to 2.0 mm of the groove entryway 58. Detentchannels 60, 62 each have a radius of curvature R2 within a preferredrange of 0.2 to 0.5 mm. An inward detent groove portion 64 is formedhaving a radius of curvature R1 within a preferred range of 1.1 to 1.9mm and a cross-sectional nominal width D1 within a preferred range of2.2 to 3.8 mm.

As best seen from FIGS. 8D, 9, 10A and 10B, the tire further formed toprovide one or more compression ribs 66 extending the circumference ofand projecting into the groove 56. The ribs 66 form a pattern of ribs ofprescribed pitch, frequency, and location as will be explained. For thepurpose of explanation, the seven compression ribs are referred togenerally by numeral 66 in the first rib profile pattern shown, andspecifically by the rib designations D0 through D6. The ribs D0 throughD6, as will be explained, are formed in a preferred sequence and pitchpattern in order to render the pumping of air through the tubepassageway 43 more efficient. The ribs 66 each have a unique andpredetermined height and placement within the pattern and, as shown inFIG. 8D, project outward into the groove 56 at a radius R3 (FIG. 8A)within a preferred range of 0.95 to 1.6 mm.

With reference to FIGS. 1, 2, 3A through 3C, and 4A through E, theperistaltic pump assembly 14 further includes an inlet device 68 and anoutlet device 70 spaced apart approximately 180 degrees at respectivelocations along the circumferential air tube 42. The outlet device 70has a T-shaped configuration in which conduits 72, 74 direct air to andfrom the tire cavity 40. An outlet device housing 76 contains conduitarms 78, 80 that integrally extend from respective conduits 72, 74. Eachof the conduit arms 78, 80 have external coupling ribs 82, 84 forretaining the conduits within disconnected ends of the air tube 42 inthe assembled condition. The housing 76 is formed having an externalgeometry that complements the groove 56 and includes a flat end 86, aradius generally oblong body 88, and outwardly projecting longitudinaldetent ribs 90. So configured, the housing 76 is capable of closereceipt into the groove 56 at its intended location with the ribs 90registering within the groove 56 as represented in FIG. 8A.

The inlet device 68 as seen in FIGS. 1, 2, 4A through 4E includes anelongate outward sleeve body 94 joining to an elongate inward sleevebody 96 at a narrow sleeve neck 98. The outward sleeve body is generallytriangular in section. The inward sleeve body 96 has an externalgeometry of oblong section complementary to the groove 56 and includes apair of detent ribs 100 extending longitudinally along the body 96. Anelongate air entry tube 101 is positioned within the inward sleeve body96 and includes opposite tube ends 102 and a pattern of entry apertures104 extending into a central tube passageway. External ribs 106, 108secure the tube ends 102 into the air tube 42 opposite the outlet device70.

As will be appreciated from FIGS. 6A, 6B, 7A, 7B, 8A through D, the pumpassembly 14 comprising the air tube 42 and inlet and outlet devices 68,70 affixed in-line to the air tube 42 at respective locations 180degrees apart, is inserted into the groove 56. The groove 56 is locatedat a lower sidewall region of the tire that, when the tire 12 is mountedto the rim 16, positions the air tube 42 above the rim flange ends 26.FIG. 8B shows the air tube 42 diametrically squeezed and collapsed toaccommodate insertion into the groove 56. Upon full insertion, as shownin FIG. 8C, the ribs 52, 54 register within the groove channels 60, 62and the flat outer end 48 of the tube 42 is generally coplanar with theouter surface of the sidewall of the tire 12. Once fully inserted, theair passageway 43 of the tube 42 elastically restores into an opencondition to allow the flow of air along the tube during operation ofthe pump.

Referring to FIGS. 1, 2, 5A, 5B, 6A, 6B, 7A, 7B, 8A through 8D, theinlet device 68 and the outlet device 70 are positioned within thecircumference of the circular air tube 42 generally 180 degrees apart.The tire 12 with the tube 42 positioned within groove 56 rotates in adirection of rotation 110, causing a footprint 120 to be formed againstthe ground surface 118. A compressive force 124 is directed into thetire from the footprint 120 and acts to flatten a segment of the airtube passageway 43 opposite the footprint 120 as shown at numeral 122.Flattening of the segment of the passageway 43 forces air from thesegment along tube passageway 43 in the direction shown by arrow 116,toward the outlet device 70.

As the tire continues to rotate in direction 110 along the groundsurface 118, the tube 42 will be sequentially flattened or squeezedopposite the tire footprint segment by segment in a direction oppositeto the direction of tire rotation 110. A sequential flattening of thetube passageway 43 segment by segment will result and cause evacuatedair from the flattened segments to be pumped in the direction 116 withintube passageway 43 to the outlet device 70. Air will flow through theoutlet device 70 and to the tire cavity as shown at 130. As referencedby arrow 130, air exiting the outlet device is routed to the tire cavity40 and serves to re-inflate the tire to a desired pressure level. Avalve system to regulate the flow of air to the cavity when the airpressure within the cavity falls to a prescribed level is shown anddescribed in pending U.S. patent applicant Ser. No. 12/775,552, filedMay 7, 2010, and incorporated herein by reference.

With the tire rotating in direction 110, flattened tube segments aresequentially refilled by air flowing into the inlet device 68 in thedirection 114 as shown by FIG. 5A. The inflow of air into the inletdevice 68 and then into the tube passageway 43 continues until theoutlet device 70, rotating counterclockwise as shown with the tirerotation 110, passes the tire footprint. 120. FIG. 5B shows theorientation of the peristaltic pump assembly 14 in such a position. Inthe position shown, the tube 42 continues to be sequentially flattenedsegment by segment opposite the tire footprint by compressive force 124.Air is pumped in the clockwise direction 116 to the inlet device 68where it is evacuated or exhausted outside of the tire. Passage ofexhaust air as shown at 128 from the inlet device 68 is through thefilter sleeve 92 which is formed of a cellular or porous material orcomposite. Flow of air through the sleeve 92 and into the tube 101 isthus cleansed of debris or particulates. In the exhaust or reverse flowof air direction 128, the sleeve 92 is cleansed of trapped accumulateddebris or particles within the porous medium. With the evacuation ofpumped air out of the inlet device 68, the outlet device is in theclosed position and air does not flow to the tire cavity. When the tirerotates further in counterclockwise direction 110 until the inlet device44 passes the tire footprint 120 (as shown in FIG. 5A), the airflowresumes to the outlet device 70 and causes the pumped air to flow outand into the tire cavity 40. Air pressure within the tire cavity is thusmaintained at a desired level.

FIG. 5B illustrates that the tube 42 is flattened segment by segment asthe tire rotates in direction 110. A flattened segment 134 movescounterclockwise as it is rotated from the footprint while an adjacentsegment 132 moves opposite the tire footprint and is flattened.Accordingly, the progression of squeezed or flattened tube segments canbe seen to move air toward the outlet device 70 (FIG. 5A) or the inletdevice 68 (FIG. 5B) depending on the rotational position of the tirerelative to such devices. As each segment is moved by tire rotation awayfrom the footprint 120, the compression forces within the tire from thefootprint region are eliminated and the segment is free to resilientlyreconfigure into an unflattened state as it refills with air frompassageway 43. FIGS. 7A and 7B show a segment of the tube 42 in theflattened condition while FIGS. 6A and 6B show the tube segment in anexpanded, unflat configuration prior and after leaving a locationopposite the tire footprint. In the original non-flattenedconfiguration, segments of the tube 42 resume an oblong generallyelliptical shape in section.

The above-described cycle is then repeated for each tire revolution,half of each rotation resulting in pumped air going to the tire cavityand half of the rotation the pumped air is directed back out the inletdevice filter sleeve 92 to self-clean the filter. It will be appreciatedthat while the direction of rotation 110 of the tire 12 is as shown inFIGS. 5A and 5B to be counterclockwise, the subject tire assembly andits peristaltic pump assembly 14 will function in like manner in a(clockwise) reverse direction of rotation as well. The peristaltic pumpis accordingly bi-directional and equally functional with the tireassembly moving in a forward or a reverse direction of rotation.

A preferred location for the air tube assembly 14 is as shown in FIGS.5A, 5B, 6A, 6B, 7A and 7B. The tube 42 is located within the groove 56in a lower region of the sidewall 30 of the tire 12. So located, thepassageway 43 of the tube 42 is closed by compression strain bending thesidewall groove 56 within a rolling tire footprint as explained above.The location of the tube 42 in the sidewall 30 affords the user freedomof placement and avoids contact between the tube 42 and the rim 16. Thehigher placement of the tube 42 in the sidewall groove 56 uses the highdeformation characteristics of this region of the sidewall as it passesthrough the tire footprint to close the tube.

The configuration and operation of the groove sidewalls, and inparticular the variable pressure pump compression of the tube 42 byoperation of ridges or compression ribs 66 within the groove 56 will beexplained with reference to FIGS. 8A through 8D, 9, 10A and 10B. In theshown embodiment, the ridges or ribs are referred to generally bynumeral 66 and individually as D0 through D6. The groove 56 ispreferably of uniform width circumferentially along the side of the tirewith the molded in ridges D0 through D6 formed to project into thegroove 56 in a preselect sequence, pattern or array. The ridges D0through D6 act to retain the tube 42 in its preferred orientation withinthe groove 56 and also apply a variable sequential constriction force tothe tube 42.

The uniformly dimensioned pump tube 42 is positioned within the groove56 as explained previously, preferably by a procedure initiated bymechanically spreading the entryway D3 of the groove 56 apart. The tube42 is then inserted into groove enlarged opening. The opening to thegroove 56 is thereafter released to return to close into the originalspacing D3 and thereby capture the tube 42 inside the groove. Thelongitudinal locking ribs 52, 54 are thus captured into longitudinalgrooves 60, 62. The locking ribs 52, 54 resultingly operate to lock thetube 42 inside the groove 56 and prevent unwanted ejection of the tubefrom the groove during tire operation. Alternatively, if so desired, thetube 42 may be press inserted into the groove 56. The pump tube 42,being of uniform width dimensions and geometry, is capable of beingmanufactured in large quantities. Moreover, a uniform dimensioned pumptube 42 reduces the overall assembly time and material cost and thecomplexity of tube inventory. From a reliability perspective, thisresults in less chance for error.

The circumferential ridges D0 through D6 projecting into the groove 56increase in frequency (number of ridges per axial groove unit of length)toward the inlet passage end of the tube 42 represented by the outletdevice 70. Each of the ridges D0 through D6 has a common radiusdimension R4 within a preferred range of 0.15 to 0.30 mm. The spacingbetween ridge D0 and D1 is the greatest, the spacing between D1 and D2the next greatest, and so on until the spacing between ridges D5 and D6is nominally eliminated altogether. While seven ridges are shown, moreor fewer ridges may be deployed at various frequency along the groove ifdesired. The projection of the ridges into the groove 56 by radius R4serve a twofold purpose. First, the ridges D0 through D6 engage the tube42 and prevent the tube 42 from migrating or “walking” along the groove56 during tire operation from the intended location of the tube.Secondly, the ridges D0 through D6 act to compress the segment of thetube 42 opposite each ridge to a greater extent as the tire rotatesthrough its rotary pumping cycle as explained above. The flexing of thesidewall manifests a compression force through each ridge D0 through D6and constricts the tube segment opposite such ridge to a greater extentthan otherwise would occur in tube segments opposite non-ridged portionsof the groove 56. As seen in FIGS. 10A and 10B, as the frequency of theridges increases in the direction of air flow, a pinching of the tubepassageway 43 progressively occurs until the passageway constricts tothe size shown at numeral 136, gradually reducing the air volume andincreasing the pressure. As a result, with the presence of the ridges,the tube groove 56 provides variable pumping pressure within the pumptube 42 configured to have uniform dimension therealong. As such, thesidewall groove 56 may be said to constitute a variable pressure pumpgroove that functions to apply a variable pressure to a tube situatedwithin the groove. It will be appreciated that the degree of pumpingpressure variation will be determined by the pitch or ridge frequencywithin the groove 56 and the amplitude of the ridges deployed relativeto the diametric dimensions of the tube passageway 43. The greater theridge amplitude relative to tube passageway diameter, the more airvolume will be reduced in the tube segment opposite the ridge andpressure increased, and vice versa. FIG. 9 depicts the attachment of thetube 42 to the outlet device 70 and the direction of air flow on bothsides into device 70.

FIG. 11 shows a second alternative rib profile area located on bothsides of the outlet to cavity connector device 70. FIG. 12A shows anenlarged detail of the groove 56 with the alternative second rib profileand FIG. 12B shows an enlarged detail of the tube 42 pressed into thesecond rib profile. With reference to FIGS. 11, 12A, 12B, the ridges orribs D0 through D6 in the alternative embodiment have a frequencypattern similar to that described above in reference to FIGS. 10A, 10Bbut each rib is also formed having a unique respective amplitude aswell. Each of the ribs D0 through D6 is generally of semi-circularcross-section having a respective radius of curvature R1 through R7respectively. The change radii of curvatures of ridges or ribs D0through D6 are within preferred exemplary ranges: Δ=0.02 to 0.036 mm.

The number of ridges and respective radii of each may be constructedoutside the preferred ranges above to suit a particular dimensionpreference or application if desired. The increasing radius of curvaturein the direction of air flow results in the ribs D0 through D6projecting at an increasing amplitude and to an increasing extent intothe tube channel 43 toward the outlet device 70. As such, the passageway43 will constrict to a narrower region 138 toward the outlet device andcause a commensurately greater increase in air pressure from a reductionin air volume. The benefit of such a configuration is that the tube 42may be constructed smaller than otherwise necessary in order to achievea preferred desired air flow pressure along the passageway and into thetire cavity from the outlet device 70. A smaller sized tube 42 iseconomically and functionally desirable in allowing a smaller groove 56within the tire to be used, whereby resulting a minimal structuraldiscontinuity in the tire sidewall.

FIGS. 13A through C show a second embodiment of a tube 42 and groove 56detail in which the detent ribs 90 in the FIGS. 8A through 8C embodimentare eliminated as a result of rib and groove modification. In the secondembodiment of FIGS. 13A through 13C, the tube 42 is configured having anexternal geometry and passageway configuration having indicateddimensions within preferred ranges specified as follows:

D1=2.2 to 3.8 mm;

D2=0.5 to 0.9 mm;

D3=0.8 to 1.0 mm;

R4=0.15 to 0.30 mm;

L1=3.65 to 3.8 mm;

L2=2.2 to 2.3 mm;

L3=1.8 to 2.0 mm.

The above ranges are preferred exemplary values that may be modified tosuit a particular dimensional preference, tire geometry, or tireapplication if desired. As shown, the external configuration of the tube42 includes beveled surfaces 138, 140 adjoining the end surface 48;parallel and opposite straight intermediate surfaces 142, 144 adjoiningthe beveled surfaces 138, 140, respectively; and a radius nose orforward surface 146 adjoining the intermediate surfaces. As seen fromFIGS. 13B and 13C, the tube 42 is compressed for press insertion intothe groove 56 and, upon full insertion, expands. The constricted openingof the groove 56 at the sidewall surface functions to retain the tube 42securely within the groove 56.

FIGS. 14A through 14C show a third alternative embodiment of a tube 42and groove 56 configuration. FIG. 14A is an enlarged view of the thirdembodiment detail; FIG. 14B a detail view showing the third embodimenttube 42 being compressed and inserted into the groove 56; and FIG. 14C adetail view showing the tube 42 fully inserted into the groove 56. Thetube 42 is generally of elliptical cross-section inserting into alike-configured groove 56. The groove 56 is formed having a narrowentryway formed between opposite parallel surfaces 148, 150. In thethird embodiment of FIGS. 14A through 14C, the tube 42 is configuredhaving an external geometry and passageway configuration having noteddimensions within preferred ranges specified as follows:

D1=2.2 to 3.8 mm;

D2=0.5 to 0.9 mm;

D3=0.8 to 1.0 mm;

R4=0.15 to 0.30 mm;

L1=3.65 to 3.8 mm;

L2=2.2 to 2.3 mm;

L3=1.8 to 2.0 mm.

The above ranges are preferred exemplary values that may be modified tosuit a particular dimensional preference, tire geometry, or tireapplication if desired.

FIGS. 15A through 15C show a fourth alternative embodiment of a tube 42and groove 56 configuration. FIG. 15A is an enlarged view of the fourthembodiment detail; FIG. 15B a detail view showing the fourth embodimenttube 42 being compressed and inserted into the groove 56; and FIG. 15C adetail view showing the tube 42 fully inserted into the groove 56. Thetube 42 is generally of parabolic cross-section inserting into alike-configured groove 56. The groove 56 is formed having an entrywaysized to closely accept the tube 42 therein. The ridges 66 engage thetube 42 once it is inserted into the groove 56. In the fourth embodimentof FIGS. 15A through 15C, the tube 42 is configured having an externalgeometry and passageway configuration having noted dimensions withinpreferred ranges specified as follows:

D1=2.2 to 3.8 mm;

D2=0.5 to 0.9 mm;

D3=2.5 to 4.1 mm;

L1=3.65 to 3.8 mm;

L2=2.2 to 2.3 mm;

L3=1.8 to 2.0 mm.

The above ranges are preferred exemplary values that may be modified tosuit a particular dimensional preference, tire geometry, or tireapplication if desired.

From the forgoing, it will be appreciated that the subject inventionprovides a bi-directionally peristaltic pump for air maintenance of atire. The circular air tube 42 flattens segment by segment and closes inthe tire footprint 100. The air inlet device 68 may include an outerfilter sleeve 92 formed of porous cellular material and thereby renderdevice 68 as self-cleaning. The outlet device 70 employs a valve unit(see co-pending U.S. patent application Ser. No. 12/775,552, filed May7, 2010, incorporated herein by reference). The peristaltic pumpassembly 14 pumps air under rotation of the tire in either direction,one half of a revolution pumping air to the tire cavity 40 and the otherhalf of a revolution pumping air back out of the inlet device 68. Theperistaltic pump assembly 14 may be used with a secondary tire pressuremonitoring system (TPMS) (not shown) of conventional configuration thatserves as a system fault detector. The TPMS may be used to detect anyfault in the self-inflation system of the tire assembly and alert theuser of such a condition.

The tire air maintenance system further incorporates a variable pressurepump groove 56 configured having one or more inwardly directed ridges orribs that engage and compress a segment of the air tube 42 opposite tosuch rib(s). The pitch or frequency of the rib series is preferred toincrease toward the outlet device 70 to gradually reduce the air volumewithin the passageway 43 by compressing the tube 42. The reduction inair volume increases the air pressure within the tube passageway 43 andthereby facilitates a more efficient air flow from the tube into thetire cavity. The increase in tube pressure is achieved by engagement bythe ribs 66 of the groove 56 and the tube 42 having uniform dimensionsalong the tube length. The tube 42 may thus be made of uniform dimensionand of relatively smaller size without compromising the flow pressure ofair to the tire cavity necessary to maintain tire air pressure. Thepitch and amplitude of the ridges 66 may both be varied to betterachieve the desired pressure increase within the tube passageway.

Variations in the present invention are possible in light of thedescription of it provided herein. While certain representativeembodiments and details have been shown for the purpose of illustratingthe subject invention, it will be apparent to those skilled in this artthat various changes and modifications can be made therein withoutdeparting from the scope of the subject invention. It is, therefore, tobe understood that changes can be made in the particular embodimentsdescribed which will be within the full intended scope of the inventionas defined by the following appended claims.

1. A tire assembly comprising: a tire having a tire cavity, first and second sidewalls extending respectively from first and second tire bead regions to a tire tread region; an elongate sidewall groove extending into the first tire sidewall from an outward first sidewall surface; the sidewall groove bounded by groove sidewalls, the groove further having at least one longitudinally adjacent elongate locking detent extending at least partially along the groove parallel to a groove longitudinal axis; an elongate air tube positioned within the elongate sidewall groove in contacting engagement with the groove sidewalls; at least one elongate locking rib extending from a side of the air tube and having a complementary external configuration to the groove locking detent, the locking rib operably residing within the groove locking detent to deter lateral movement of the air tube within the sidewall groove.
 2. The tire assembly of claim 1, further comprising at least a pair of locking ribs extending from opposite sides of the air tube, and at least a pair of locking detents longitudinally adjacent along opposite sides of the sidewall groove, the locking ribs each having a complementary external configuration to a respective groove locking detent and each locking detent operably residing within the respective groove locking detent to deter lateral movement of the air tube within the sidewall groove.
 3. The tire assembly of claim 2, wherein the groove locking detents are within the first tire sidewall and oriented to extend along a path substantially parallel to the first sidewall outward surface.
 4. The tire assembly of claim 3, wherein the air tube locking ribs extend substantially coterminous with the air tube.
 5. The tire assembly of claim 4, wherein the air tube and the sidewall groove extend along a complementary substantially circular path.
 6. The tire assembly of claim 5, wherein the groove locking detents and the tube locking ribs extend along a complementary substantially circular path.
 7. The tire assembly of claim 6, wherein the groove locking detents and the air tube locking ribs are substantially semi-circular in cross-section.
 8. The tire assembly of claim 1, wherein the first sidewall groove comprises at least one annular projecting ridge extending from a groove sidewall segment into the groove air passageway, the one projection ridge operatively positioned to engage a respective opposite segment of the air tube and deter axial movement of the air tube within the first sidewall groove.
 9. The tire assembly of claim 8, wherein further comprising a plurality of projecting annular ridges spaced apart along the first sidewall groove and extending into the air passageway to engage opposite respective segments of the air tube and deter axial movement of the air tube.
 10. The tire assembly of claim 8, wherein the one annular projecting ridge and the at least one locking rib extend along respective paths mutually oriented at substantially ninety degrees.
 11. The tire assembly of claim 10, further comprising at least a pair of locking ribs extending from opposite sides of the air tube, and at least a pair of locking detents longitudinally adjacent along opposite sides of the sidewall groove, the locking ribs each having a complementary external configuration to a respective groove locking detent and each locking detent operably residing within the respective groove locking detent to deter lateral movement of the air tube within the sidewall groove.
 12. The tire assembly of claim 11, wherein the groove locking detents are within the first tire sidewall and oriented to extend along a path substantially parallel to the first sidewall outward surface.
 13. The tire assembly of claim 12, wherein the air tube locking ribs extend substantially coterminous with the air tube.
 14. The tire assembly of claim 13, wherein the air tube and the sidewall groove extend along a complementary substantially circular path.
 15. The tire assembly of claim 14, wherein the groove locking detents and the tube locking ribs extend along a complementary substantially circular path.
 16. The tire assembly of claim 15, wherein the groove locking detents and the air tube locking ribs are substantially semi-circular in cross-section. 